If it continues to get worse and all of your chickens begin to get sick, then they might have what mine had. It was a respritory issue. They made the same sounds, would sneeze, feathers around there neck looked wet sometimes and I even had one die. I had to treat them with duramycin, I guess its like a penicilian for chickens. I also learned that I had the coop covered up too much and it wasn't getting the proper ventilation. That may have been part/mostly the cause. If you end up having to treat them with that make sure to do some research first. You can't eat eggs for a while and some other stuff you will want to know. I got it from my local feed store. Hope they get better for you.